1. Field of the Invention
The present invention relates to a vehicle wheel with reduction in noise due to air column resonation (cavity resonation).
2. Description of the Related Art
A vehicle wheel with reduction in a noise level due to air column resonation (cavity resonation) is known.
Generally, the air column resonation generated in an air chamber of a tire (hereinafter referred to as tire air chamber) may generate road noise of a vehicle. The air column resonation is a phenomenon in which random vibrations of a tire caused by roughness of a road surface cause vibrations of the air in the tire air chamber. As a result, a resonation phenomenon occurs, which generates resonance.
JP 2004-90669 A discloses a vehicle wheel capable of reducing noise caused by the air column resonation. The vehicle wheel has a plurality of sub-air chambers in a circumferential direction of the rim. More specifically, a lid covers an annular space formed between a annular vertical wall vertically extending from a well and extends in the circumferential direction of the rim and a side wall of the well extending to a bead seat. A plurality of sub-air chambers are formed by sectioning the annular space, defined by the lid, the well, and vertical wall, with partition walls equi-distantly disposed in the circumferences of the rim. The tire air chamber is communicated with each sub-air chamber through communication holes formed in the lid. This vehicle wheel is capable of reducing the air column resonance in the tire air chamber by forming a Helmholtz resonator with the communication holes and the sub-air chambers.
However, there is a problem in this prior art vehicle wheel in mass production in consideration of securing air tightness and increase in manufacturing man-hour and manufacturing cost. This is because it is necessary to connect a plurality of partition walls and the lid to the wheel with the vertical wall extending vertically from the well by welding, adhering, and fitting with the air tightness being kept.
As a material of the members in the sub air chamber a metal, a plastic, etc. can be used. However, in consideration of weight reduction, mass productivity, air tightness in the sub air chambers a plastic, which allows blow molding, is preferable.
However, if a plastic is used as the material of the sub air chamber, a noise reduction performance cannot be obtained sufficiently as the Helmholtz resonator because a volume of the sub air chamber increases or decreases when variation in the air pressure varying alternately between plus and negative sides in the tire air chamber by the air column resonation because the wall members forming the sub air chambers has a lower plane stiffness than the case where a metal plate is used.
In this case, it can be considered to increase a thickness of the wall members in order to increase the plane stiffness. However, increase in the thickness of the wall members increases a weight of the sub air chambers, which results in increase in a magnitude of centrifugal force acting on the members of the sub air chamber. This results in increase in the strength of the members for fixing the sub air chamber to the well.